Preserve inferred project ATA state

[Jake Bailey (jakebailey)]

I noticed in our scripts dir (no tsconfig), that clicking on a file flashed errors. I closed it, opened another file, and the errors appeared and disappeared again! If I opened another file without closing the first, that one was fine.

The issue is that we lose the ATA state when inferred projects go away, so reopening causes ATA to happen again.

Save the state and apply it directly to inferred projects if present.

[Copilot]

Copilot review overview

🟡 Changes recommended

Cached ATA state can be incorrectly reused across unrelated roots or changed manifests.

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Review effort: Balanced
Findings: 1

Open (1)

• Prevent stale ATA state reuse across roots and manifests · New

What changed in this PR

Preserves ATA results when inferred projects are recreated.

Changes:

• Stores and restores inferred-project typings state.
• Adds a reopening regression test.

File	Description
projectcollectionbuilder.go	Transfers cached ATA state.
projectcollection.go	Stores cached ATA state.
project.go	Defines ATA state capture/application.
ata/​ata_test.go	Tests immediate typings restoration.

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[Copilot]

Copilot review overview

🟡 Changes recommended

Cache validation misses filesystem invalidation and changed ATA inputs, and content-mapped roots use incompatible hashes.

Get a fresh assessment by requesting another Copilot review.

Review effort: Balanced
Findings: 3

Open (3)

• Validate compatible hashes for content-mapped ATA cache reuse · New
• Clear cached ATA state when InvalidateAll has no changes · New
• Prevent stale ATA state reuse across roots and manifests

Previously missed (1)

In code that hasn't changed since last review

Invalidate ATA cache when inferred-project options change

tsc/​internal/​project/​project.go:214

Root names and contents are not the complete ATA input. If inferred-project compiler options change while no inferred project exists, the cached state is left untouched; reopening the same roots applies typings computed under the old options before ATA is queued in the background (and resolution-affecting options can also change the unresolved-import set). Preserve and compare the relevant command-line/mapping inputs, or invalidate this cache when those inputs change.

[Copilot]

Copilot review overview

🟡 Changes recommended

Stale ATA results can still overwrite invalidated configured or synthetic project state, and key new branches lack regression coverage.

Get a fresh assessment by requesting another Copilot review.

Review effort: Balanced
Findings: 1 · 2

Open (3)

• Guard stale ATA results after all project invalidations · New
• Test omission of unrelated cached typings · New
• Add coverage for no-active-project retention results · New

Resolved since last review (3)

• Clear cached ATA state when InvalidateAll has no changes
• Validate compatible hashes for content-mapped ATA cache reuse
• Prevent stale ATA state reuse across roots and manifests